Effects of birth weight, sex and neonatal glucocorticoid overexposure on glucose-insulin dynamics in young adult horses.

This research examines how certain conditions during the early life of horses, such as birth weight, sex and overexposure to glucocorticoid, influence glucose-insulin dynamics in adulthood.

Background

The study’s primary focus is on how various factors influence the adult metabolic phenotype in horses. The researchers in this study considered factors such as birth weight, sex, and neonatal glucocorticoid overexposure that occur shortly after birth. Previously, these influential factors and their effects on glucose-insulin dynamics in the later life of horses were largely unknown.

Methods

• A group of term foals were subjected to different types of treatments immediately after birth. They were administered either saline as a control group or adrenocorticotropic hormone (ACTH) as a treatment group. The purpose of ACTH was to increase cortisol levels comparable to stressed neonates.
• To assess the differing effects of the treatments, insulin secretion and sensitivity were measured at two different stages, one year and two years of age. The exogenous glucose administration was used to measure insulin secretion, while a hyperinsulinaemic-euglycaemic clamp was employed to determine insulin sensitivity.

Findings

• The results indicated that glucose-stimulated insulin secretion was less in male foals than females at 1 and 2 years, however, the glucose tolerance did not vary by sex.
• Insulin sensitivity was higher in female foals at one year, but there was no difference noticed between males and females at two years of age.
• Birth weight was found to be inversely related to the area under the glucose curve, which suggests that lower birth weight foals have a higher glucose response over time, and was positively correlated to insulin sensitivity at two years but not at one year of age.
• Importantly, neonatal glucocorticoid overexposure, as induced by the ACTH treatment, did not affect overall glucose tolerance, insulin secretion, or insulin sensitivity at either age. However, it was noted that this treatment did affect insulin receptor abundance in specific skeletal muscles in the 2-year-old horses.

Conclusion

Based on the results, the researchers concluded that glucose-insulin dynamics in young adult horses are affected by both sex and genetic and early-life environmental factors. The implications of this research suggest that modifying these factors in early life stages could influence the metabolic health of horses in adulthood. This could be of significance for both horse breeding practices and potential interventions for metabolic disorders in horses.